For fuel cell systems installed in electric vehicles, etc., in order to respond to a sudden change in load beyond the power-generating capacity of a fuel cell, a so-called hybrid fuel cell system provided with a load drive circuit and a battery has been developed, the hybrid fuel cell system being configured such that: the output voltage of the battery is increased or decreased through a voltage converter and then connected to the output terminal of the fuel cell; and the output of the battery can be supplied to a load device.
In this type of hybrid fuel cell system, various sensors for measuring the values of voltage, current or electric power are provided, in particular, for the voltage converter, and the values measured by those sensors are used for the system control. If an abnormal value is included in such measured values from the sensors, it would affect the system control, and might result in unfavorable conditions for the system operation.
In view of the above, the idea of calculating differences between the respective voltage values detected by the input-side and output-side voltage sensors of a voltage converter and the voltage sensor of a battery, analyzing the differences through comparison with each other, and thereby detecting an abnormal condition in the sensors and specifying which sensor is in an abnormal condition, is disclosed in, for example, Japanese laid-open patent publication No. 2004-364404 (see Patent Literature 1).
Patent Literature 1: Japanese laid-open patent publication No. 2004-364404